1. Field of the Invention
This invention relates to a multiple input warning system for a motor vehicle and, more particularly, to a warning display system that operates with the vehicle ignition off.
2. Prior Art
Special purpose multiple input warning systems are well represented in the prior art. One example of these specialized warning systems include U.S. Pat. No. 3,899,770 issued to Slotkowski and assigned to Ford Motor Company. That invention relates to a system for activating an audible and/or visual warning indicator in response to the vehicle ignition key being placed in a special condition and then the occurrence of a particular vehicle condition or malfunction sensed by one or more of a plurality of input signals and/or condition indicating devices. Another example of a vehicle warning system includes U.S. Pat. No. 4,550,303 issued to Steele and assigned to General Motors Corporation. That invention relates to the use of a latch for maintaining power applied to a failure lamp that is activated in response to the sensing of a vehicle failure, even after the vehicle ignition is switched off. Still another example of a centralized vehicle alarm system is disclosed in U.S. Pat. No. 4,234,866 issued to Kuroda et al and assigned to Nissan Shataico, Ltd.
Other comprehensive motor vehicle diagnostic and monitoring systems are disclosed in U.S. Pat. No. 4,277,772 assigned to General Motors Corporation, and U.S. Pat. No. 4,497,057 assigned to Nippondenso Co. Ltd. Both of these inventions relate to the use of separate computers that are programmed to sense signals emitted by remote sensors indicative of system or component failures. Complex memory systems and diagnostics are used for detecting and/or confirming the failures
While each of these warning systems provides a satisfactory solution to the specific problem which they address, none of the above prior art references provides a suitable and cost effective solution to the problem of providing a highly visible and reliable warning system, which is integrated with the vehicle operational display, in a motor vehicle in which the ignition switch is turned to the off position.
It is therefore an object of the present invention to provide a vehicle warning display that is integrated (both functionally and physically) into the master driver information display used for vehicle operational parameters (such as speed, cooling system temperature, electrical system charging, etc.). In order to reduce power consumption and improve display clarity, it is highly desirable to utilize the existing driver information display system for illuminating the key warning indicators, while at the same time blanking or disabling the operational display indicators.
The use and display of safety related vehicle warning indicators (such as left and right turn signals, hazard warning signals, high beam headlight indicators, door ajar indicators, etc.) is often required during or immediately after conditions of heavy electrical system loading. For example, in conditions involving heavy ice and snow storms it is not unusual for the vehicle electrical systems to be fully taxed during the use of windshield wipers, headlights, heater/wind screen defrosters and fans, rear window resistive defrosters, passenger compartment heating fans, radio/audio systems, etc. Under these conditions the driver often finds it necessary to pull off the road for changing tires, waiting for better weather conditions assisting other motorists in distress, etc. During these times the vehicle operator often elects to turn the ignition switch off in order to conserve battery power.
It is important to warn the driver of key vehicle conditions, such as the continued use of turn signals, hazard warning indicators, high beam headlights, door ajar, etc. even when the ignition switch is turned off. Under these circumstances the driver's attention is often diverted to other events occurring in the external environment, and therefor it is desirable to provide a clear and highly visible display of these warnings signals without displaying other extraneous information.
While other prior art inventions have solved this problem through the use of separate indicator warning lights spaced about the dashboard, they often require additional computer control circuitry which increases both cost and electrical power consumption. Furthermore, in modern vehicles the space available for operator information displays has been considerably reduced, thereby mandating a higher degree of integration of information displays.